The present invention relates generally to producing forces in force feedback interface devices, and more particularly to the output and control of vibrations and similar force sensations from actuators in a force feedback interface device.
Using an interface device, a user can interact with an environment displayed by a computer system to perform functions and tasks on the computer, such as playing a game, experiencing a simulation or virtual reality environment, using a computer aided design system, operating a graphical user interface (GUI), or otherwise influencing events or images depicted on the screen. Common human-computer interface devices used for such interaction include a joystick, mouse, trackball, steering wheel, stylus, tablet, pressure-sensitive ball, or the like, that is connected to the computer system controlling the displayed environment.
In some interface devices, haptic or tactile feedback is also provided to the user, also known as “force feedback.” These types of interface devices can provide physical sensations which are felt by the user using the controller or manipulating the physical object of the interface device. One or more motors or other actuators are used in the device and are connected to the controlling computer system. The computer system controls forces on the force feedback device in conjunction and coordinated with displayed events and interactions on the host by sending control signals or commands to the force feedback device and the actuators.
Many low cost force feedback devices provide forces to the user by vibrating the manipulandum and/or the housing of the device that is held by the user. The output of simple vibration force feedback requires less complex hardware components and software control over the force-generating elements than does more sophisticated haptic feedback. For example, in many current controllers for game consoles such as the Sony Playstation and the Nintendo 64, a motor is included in the controller which is energized to provide the vibration forces. An eccentric mass is positioned on the shaft of the motor, and the shaft is rotated quickly to cause the motor and the housing of the controller to vibrate. The host computer (console) provides commands to the controller to turn the vibration on or off or to increase or decrease the frequency of the vibration by varying the rate of rotation of the motor. These current implementations of vibrotactile feedback, however, tend to be limited and produce low-bandwidth vibrations that tend to all feel the same, regardless of the different events and signals used to command them. The vibrations that these implementations produce also cannot be significantly varied, thus severely limiting the force feedback effects which can be experienced by a user of the device.